Introduction:
Bacteria play a crucial role in the process of converting milk into curd. Lactobacillus, a type of bacteria, is primarily responsible for this conversion. However, not all bacteria are harmful for curd.

Role of Lactobacillus in curd formation:
- Lactobacillus is a beneficial bacteria that helps in the fermentation process of milk to produce curd.
- This bacteria converts lactose, the sugar present in milk, into lactic acid, which gives curd its characteristic tangy flavor and thick texture.
- Lactobacillus also produces compounds that enhance the nutritional value of curd, such as vitamins and enzymes.

Harmful bacteria in curd:
- While lactobacillus is beneficial for curd formation, other harmful bacteria can contaminate curd if proper hygiene practices are not followed during the curd-making process.
- Harmful bacteria can cause spoilage of curd, leading to off-flavors, bad odors, and potential health risks if consumed.

Preventing contamination:
- To prevent the growth of harmful bacteria in curd, it is essential to maintain clean utensils, hygienic conditions, and proper temperature control during the curd-making process.
- Using pasteurized milk and starter cultures containing beneficial bacteria like lactobacillus can help ensure the production of safe and healthy curd.
In conclusion, while bacteria like lactobacillus are essential for curd formation, proper hygiene practices are crucial to prevent the growth of harmful bacteria that can contaminate curd. By understanding the role of bacteria in curd-making and following good hygiene practices, one can enjoy the nutritional benefits of this dairy product without any health risks.